Ruckman was the pastor of Bible Baptist Church in Pensacola, and his writings and recorded sermons are published by his Bible Baptist Bookstore.[4] Like his father, Peter Ruckman demonstrated artistic talent early in life, and he often illustrated his sermons in chalk and pastels while preaching.[5] In 1965, Ruckman founded Pensacola Bible Institute, in part because of disagreements with other institutions with regard to Biblical translations. Ruckman continued teaching a Sunday school class and participating in other church-related activities until April 2015, when he retired at 93.[6]

Ruckman married three times, the first two marriages ending in divorce.[7] He had ten children.[8] His son P.S. Ruckman Jr. was a professor and authority on presidential pardons until his death in March 2018.[9]

According to David G. Burke, Ruckman was a believer in "King James Onlyism".[10] Ruckman said that the King James Version of the Bible, the "Authorized Version" ("KJV" or "A.V."), provided "advanced revelation" beyond that discernible in the underlying Textus Receptus Greek text, believing the KJV represented the final authority in all matters of faith and practice.[11]

Ruckman distinguished between the Textus Receptus of the KJV, and the numerically fewer manuscripts of the Alexandrian text-type underlying most modern New Testament versions. Ruckman characterized those who endorse the latter as members of the "Alexandrian Cult" who believe that while the autographs were God-inspired, they have been lost, and that therefore his opponents believe there to be "no final, absolute written authority of God anywhere on this earth".[12] Ruckman also believed that the Septuagint was a hoax perpetrated by the "Alexandrian cult" under the leadership of the Church FatherOrigen Adamantius (as part of his Hexapla) in the 3rd century AD in order to subvert belief in the integrity of the Bible.[13]

Ruckman's position on the exclusive authority of the KJV was strongly opposed by many supporters of biblical inerrancy, including signers of the Chicago Statement on Biblical Inerrancy who specifically "deny that any essential element of the Christian faith is affected by the absence of the autographs [and] further deny that this absence renders the assertion of Biblical inerrancy invalid or irrelevant". The majority of those who support the King James Only movement reject Ruckman's position that the English KJV is superior to existing Hebrew and Greek manuscripts,[14] and they also criticize Ruckman because "his writings are so acerbic, so offensive and mean-spirited that the entire movement has become identified with his kind of confrontational attitude".[15]

The website of Ruckman's press notes that although some have called his writings "mean spirited", "we refer to them as 'truth with an attitude'".[16] According to Beacham and Bauder, "Ruckman is without any doubt the most caustic and abusive among King James-Only partisans".[17]James R. White states in his book The King James Only Controversy that to call Ruckman "outspoken is to engage in an exercise in understatement. Caustic is too mild a term; bombastic is a little more accurate. ... There is no doubt that Peter S. Ruckman is brilliant, in a strange sort of way. His mental powers are plainly demonstrated in his books, though most people do not bother to read far enough to recognize this due to the constant stream of invective that is to be found on nearly every page. And yet his cocky confidence attracts many people to his viewpoint."[18]

^Peter Ruckman, The Christian's Handbook of Manuscript Evidence (Pensacola: Pensacola Bible Press, 1990), 126; the website of David Cloud, another KJV-Only proponent, says that "For good or for bad, Peter Ruckman’s name is intertwined with the defense of the King James Bible."

^"It was at this point, on the verge of suicide, that Ruckman began to hear a series of voices. He himself interprets the voices as being the voice of God, for the most part. He thinks that he learned to distinguish the voice of God from the voice of demons through yoga." The Ruckman Conspiracy (Collingswood, N. J.: The Bible for Today, 1989), 3.

^By his own admission, Ruckman's earlier family life was turbulent: "I have had two wives desert me after fifteen years of marriage....I have been in court custody cases where seven children's futures were held in the balance; in situations where Gospel articles were being torn out of typewriters, Biblical artwork torn off the easels, women trying to throw themselves out of cars at fifty m.p.h., mailing wedding rings back in the middle of revival services, cutting their wrists, threatening to leave if I did not give my church to their kinfolk; deacons threatening to burn down my house and beat me up; children in split custody between two domiciles two hundred miles apart, and knock-down, drag-out arguments in the home sometimes running as long as three days." Peter Ruckman, The Last Grenade (Pensacola: Bible Baptist Bookstore, 1990), 339.

^"The LXX is nothing more than a figment of someone’s imagination. The Septuagint represents PERFECTION in FRAUD, obviously intended to deceive, and cause doubt regarding the INTEGRITY of the Word of God." Septuagint hoax

^James White, The King James Only Controversy: Can You Trust the Modern Translations? (Minneapolis: Bethany House, 1995), 1-4. White is an opponent of the KJV-Only position, but he cites such KJV-Only proponents as David Cloud. See, for instance, Cloud's website. Ruckman's position was, however, supported by Gail Riplinger.

^James R. White, The King James Only Controversy: Can You Trust the Modern Translations? (Minneapolis: Bethany House Publishers, 1995), 109. His invective has often been ad hominem. One of Ruckman's targets has been Stewart Custer, emeritus chair of the Bible department at BJU: "By far the most shameful and shocking thing about Stewart's work is not his lying (we would expect that) and his stupidity (we take that for granted, but we will document it for the reader); the most shocking thing was the performance of Robert Sumner (The Sword of the Lord) and Bob Jones, Jr. (BJU) in actually seriously recommending" his work. Peter S. Ruckman, Custer's Last Stand (Pensacola: Bible Baptist Bookstore, 1981), iii.